Anze Kopitar and Justin Williams get third-period goals for L.A., which faced 2-0 and 3-2 deficits.

The Kings' offense, dormant through the first three games of their opening-round playoff series against the St. Louis Blues, awoke Monday in time to prolong their season and their reign as Stanley Cup champions.

Justin Williams completed a two-goal rally in the third period with a deflection that withstood a video review, as the Kings barged past the Blues for a 4-3 victory at Staples Center and evened the series at two games each.

"Now it's all tied up and best of three," said center Anze Kopitar, whose first goal in 20 games, off a feed from a hard-digging Dustin Brown, had brought the Kings even at 7 minutes 14 seconds of the third period.

In scoring four goals — one more than they had totaled in losing two of the first three games of this series — the Kings put themselves on even footing for Game 5 Wednesday in St. Louis, where they will try to break an eight-game road losing streak. Game 6 will be played Friday at Staples Center.

"Going back to St. Louis down 3-1, would have been an extremely daunting task to overcome," Williams said. "I'm not saying it wasn't doable, but now we feel a lot better about ourselves. We feel a lot better having some guys put it in the back of the net tonight that need to score. And pushing them back."

The Kings found the strength to make a huge push in the third. The last time they had trailed by two goals in a playoff game and won was on April 18, 2001, against Detroit, a 4-3 overtime victory.

But in a game whose seven goals matched the total the teams had combined to score in the first three contests, nothing was impossible — even a goal by Kopitar.

He had been struggling offensively for more than a month, and even though his defensive play remained solid, no team is going to succeed without regular contributions from its No. 1 center. Kopitar took a pass from Brown and beat Blues goaltender Brian Elliott for his first goal since March 25, triggering roars from the crowd and a huge smile from the Slovenian center.

"It's hard to explain but every time you go through a drought, when you get that one you feel about a hundred pounds lighter," Kopitar said. "I felt pretty good after that."

No member of the Kings was feeling too good at the start.

David Backes gave the Blues a 1-0 lead at 1:12, capturing the rebound of a shot by Jay Bouwmeester that had caromed off the end boards and slipping it into a wide-open net. That lead became 2-0 at 4:32, with Colin Fraser serving a high-sticking penalty. T.J. Oshie scored it by deflecting a shot by defenseman Kevin Shattenkirk.

The Kings cut their deficit to 2-1 at 9:33, when Robyn Regehr got the puck up to Mike Richards, who was skating up the left side. Richards drew a defender and passed the puck perfectly to an unchecked Jeff Carter, who backhanded the puck past Elliott for his first goal of the series.

A mistake by St. Louis defenseman Jordan Leopold, who took a chance by skating deep into the offensive zone and lost the gamble, led to the Kings' second goal. Jarret Stoll tipped the puck past him and created a three-on-one break. He fed the puck to Alec Martinez, who returned the puck to Stoll on the rush. Stoll fed Dustin Penner, who had gotten behind the defense and had a clear and successful shot on Elliott.

The Blues became the first team to reach three goals in this series when Oshie scored at 5:46 of the second period.

It began when the Blues won a faceoff in their own zone, and Patrik Berglund got the puck to Vladimir Sobotka. His shot was stopped, but Oshie lifted the rebound over a fallen Jonathan Quick from deep on the right side.

That was all the Blues would score.

"Sometimes, this time of year it's about your resilience," Brown said. "We put ourselves in hard spots and we've been able to lean on each other.

"It comes back to the experience we've gone through together. It's a matter of leaning on each other to pull this thing out."

And so they did, at least on Monday. "We had a great third period. We had a great response," Williams said. "But now's not the time to relax. Now's the time to keep the pedal down."